Lift trucks are designed in a variety of configurations to perform a variety of tasks. Most tasks include the operation of a vertically movable platform to lift and lower a load, such as materials on a pallet. Lift cylinders are operable to lift and lower the load. The lift cylinders typically operate within an extendable mast.
Reach trucks and other high-lift material handling vehicles are designed to lift loads to high elevated heights. The capacity that these vehicles can lift to such heights is constrained by many factors, one of which is the buckling resistance of the lift cylinders. As the rated capacity and elevated height of the vehicle increases, lift cylinder buckling resistance can become a limiting factor due to the increased unsupported length of the piston rod. To counter this, the diameter of the piston rod and cylinder are often increased to sustain the axial buckling load induced by the load on the forks. The critical buckling load (Pcr) as defined in classical Euler buckling theory can be expressed as
                              P          cr                =                                            π              2                        ⁢            EI                                L            e            2                                              (        1        )            where E is Young's modulus, Le is the effective length of the rod, and I is the moment of inertia. In the case of round bar for example, the moment of inertia may be given by
                    I        =                              π            ⁢                                                  ⁢                          D              4                                64                                    (        2        )            for a bar of diameter D. As demonstrated by equation (1), as the diameter (D) increases, the load needed to buckle the cylinder increases. Increasing the lift cylinder size, however, can have negative performance impacts on the vehicle.
It would therefore be desirable to identify alternative systems and methods to improve the buckling resistance of the lift cylinders.